This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Albert Cunningham, PI This project will use structure-activity relationship (SAR) modeling to define groups of tissue-specific carcinogens followed by comparative toxicogenomics and proteome analyses to identify the molecular targets they interact with or influence. This subproject has three specific aims: 1. Model Development: Update existing SAR models for rodent carcinogenicity that will serve as "control" models and a set of "experimental" SAR models based on target tissue-specific chemical carcinogenesis. The control models will be based on the traditional SAR approach of contrasting carcinogens to noncarcinogens and the experimental models will be based on a new approach of contrasting chemical carcinogens from one site to those of all other sites. In essence, the control models will handle the question of "What makes a chemical a carcinogen?" and the experimental models will tackle the problem of "What makes a carcinogen target a specific tissue?" This aim will use the Core C facility (Molecular Modeling) to carry out this approach. 2. Toxicophore Identification: Based on information developed in Aim 1, we will identify toxicophore-defined sets of compounds (i.e., with similar structure and biological activity) associated with tissue-specific carcinogenesis. Then we will refine toxicophores from these models with ligand-based 3D SAR methods and develop small libraries of suitable compounds for in vitro testing. This aim will use Core C (Molecular Modeling). 3. Genome/Proteome Target Identification: Using the compounds from the toxicophore libraries developed in Aim 2 as chemical probes, we will assay site-matched cell lines in order to identify the molecular targets with which they interact. Comparative toxicogenomics and proteomics will be used to identify the specific molecular targets associated with tissue-specific carcinogenicity. This aim will use Cores B (Microarray facility).